This may give the impression that the judges are merely falling in line with the stunning (and, in my view, most welcome) reversal of public opinion on gay rights in recent years.

And so they are. When engaging in what can only loosely be called “interpretation,” the Supreme Court, and lower courts, certainly do follow the election returns, and the polls, and elite opinion, and their own political instincts.

But the remarkable fact sitting in plain view is that a single justice, Anthony Kennedy, who seems likely to ultimately determine whether states must endorse gay marriage, is far more than the “swing vote” on many enormously important and controversial issues that he is reputed to be.

It’s no secret that Kennedy’s uniquely eclectic mix of views enables him to tip the balance to the left in 5-4 decisions on politically drenched issues including gay rights, abortion, and the death penalty, and to the right on issues including states’ rights, campaign spending, and guns.

Nor is it a secret that the court has in recent decades appointed itself the most powerful policymaking body in the country on many social (and other) issues that it once left to elected officials.

Nor that Kennedy’s (and the court’s) decisions—both the liberal and the conservative ones—often strain the words of the Constitution or contradict the Founders’ understanding or both. Any decision requiring state endorsement of gay marriage would surely do both.

Indeed, the Constitution’s text is so ambiguous when refracted through 225 years of history that respectable legal arguments can be made for almost any policy outcome that a justice might favor.

But how aware are most Americans that taken together, these facts mean that a 77-year-old man whose name is recognized by only 41 percent of the public—fewer than all but one of his eight colleagues—has more power by far than any president (or justice) in history to decree the law of the land on all of the issues mentioned above? Plus other issues, including racial affirmative-action preferences, free speech, school discipline, school integration, school prayer, the death penalty, and much more.

Justice Kennedy is a smart, gregarious man, and his basically centrist political-ideological instincts on most issues may be closer to my own than those of any other current justice. Indeed, I suspect that I agree with more of Kennedy’s policy outcomes (if not the reasoning behind many of them) than do any of the conservative commentators who like his right-leaning policy preferences or the liberals who like his left-leaning policy preferences.

So why do I see something wrong with this picture?

Because the exercise of such emperor-like power by a single man—one who (like his colleagues) has never been elected to any public office would have lost his seat long ago if justices had to be reconfirmed based on their records—has very little to do either with democracy or with the written Constitution

Take, for example, the 5-4 decisions last June 25 and 26 striking down two major federal laws. Justice Kennedy, who cast the deciding vote in each case, was accused of usurping congressional power by all eight of his colleagues—the four liberals in the first case, the four conservatives in the second.

The first, Shelby County v. Holder, erased a key provision, Section 4, of the Voting Rights Act (VRA) for encroaching on states’ rights. Section 4 had required that six states of the former Confederacy, and other jurisdictions with a history of voting discrimination, clear any and all changes in voting rules with the Justice Department or a special three-judge court.

The four liberal dissenters to Kennedy and the conservatives bitterly assailed the majority opinion, written by Chief Justice John Roberts, for refusing to defer to Congress. “Hubris,” rather than “restrained and moderate decision-making,” wrote Justice Ruth Bader Ginsburg, “is a fit word for today’s demolition of the VRA.”

When liberal justices act as a continuing constitutional convention, they make it easier for conservative justices to do the same.

The second decision, United States v. Windsor, wiped out a 1996 law denying to gay couples the many federal benefits conferred by Congress on husbands and wives. Kennedy’s opinion for himself and the four liberal justices held that the law served no legitimate purpose and was motivated by “a bare congressional desire to harm a politically unpopular group.” Thus, ruled the court, the government must provide gay couples who have valid state-law marriages the same federal benefits that it confers on traditional married couples.

This time it was the four conservative dissenters’ turn to launch the same kind of attack on Kennedy that the liberals had made the day before on Kennedy and the four conservatives. “It is an assertion of judicial supremacy over the people’s representatives in Congress and the Executive,” wrote Justice Antonin Scalia. “It envisions a Supreme Court standing (or rather enthroned) at the apex of government.”

Many court-watchers have deplored Kennedy’s vote in one or the other of these decisions. Few seem to have considered the possibility that he, and the court, usurped congressional power in both of them.

The court could have used another case decided on June 26, Hollingsworth v. Perry, to rule on whether the 33 states that still refuse to endorse gay marriage must do so, as a federal district court in California had held. But the justices ducked the issue on the grounds that only representatives of the state, who had declined to appeal, had legal standing to do so.

Scalia predicted in his Windsor dissent that lower courts would—as four have now done—see the majority’s decision as a green light to require that states endorse gay marriage. “By formally declaring anyone opposed to same-sex marriage an enemy of human decency,” he wrote, “the majority arms well every challenger to a state law restricting marriage to its traditional definition.”

But Kennedy’s opinion in Windsor sowed confusion about where he was headed by mixing his stigmatizing of elected officials who oppose gay marriage with a paean to the central role of the states in defining marriage.

How will Kennedy rule when the gay-marriage issue comes before the court again, probably in 2015 or 2016?

Remember that he has now written all three of the Supreme Court’s landmark decisions in favor of gay rights. And keep your eye on the polls.

Meanwhile, bear in mind that, in the words of Felix Frankfurter, “Holding democracy in judicial tutelage is not the most promising way to foster disciplined responsibility in a people.” This may seem to imply that judicial review no longer serves a legitimate purpose and should be abandoned. But I stop short of that, for three reasons.

First, however weak the court may be as a bulwark against majoritarian tyranny, it is better than no bulwark at all. Second, three independent branches make for a more stable government than two. Third, the court has been, on balance, a vital (if most imperfect) engine of progress on race, women’s rights, gay rights, the freedoms of speech and religion, property rights, free enterprise, the privacy of the home, contraception, and much else.

Do these benefits justify continuing the gradual, seemingly irreversible arrogation of imperial power by generations of justices, including Kennedy and all eight of his current colleagues?

The answer may depend on whether they show some awareness of their own fallibility and enough respect for democratic governance to stay their hands from contriving constitutional rationales to strike down every law they don’t much fancy.

They could start by following the sage advice of my friend Jonathan Rauch, who is married to his gay partner and thus speaks with authority:

“Gay Americans are now, at long last, winning the battle for marriage equality where it counts: in the hearts and minds of our straight fellow citizens.…

“[But] the country is still about 50-50 on gay marriage, and the cause might be set back, perhaps by decades, if nine (actually, five) bureaucrats in black robes sweep in and take the issue out of the people’s hands. Even if gays are on the right side of the argument about marriage, we will land on the wrong side of the argument for democratic sovereignty—a bigger, tougher fight, and a fight we do not need to pick.”

But why should the many thousands of gay people who are denied the privileges of marriage right now have to wait until their own states’ voters see the light? Why shouldn’t the justices just do the right thing, as they did in 1967, when they struck down laws against interracial marriage in Loving v. Virginia?

In addition to Rauch’s point that in the long run, judicial imperialism might set back the cause of gay marriage, it is simply anti-democratic and illegitimate for five unelected justices to wipe out, with no basis in the Constitution’s language or history, every action of the legislative and executive branches that the five consider unfair.

Among the legions who might complain that various laws are unfair to them are adult women who want to marry polygamists, or their brothers, or sisters, or fathers; mature 17-year-olds and undocumented immigrants who want to vote; smokers who resent being exiled from indoor (and many outdoor) spaces; recreational users of cocaine; and low-skilled, hard-working employees who claim that they were laid off and left unemployed because of an increase in the minimum wage.

In addition, when liberal justices (plus Kennedy) act as a continuing constitutional convention, they make it easier for conservative justices (plus Kennedy) to do the same, and to strike down campaign-spending restrictions, various Obamacare provisions, a central provision of the Voting Rights Act, gun-control laws, acts of Congress requiring states to pay damages for various forms of discrimination, and, many decades ago, minimum-wage laws.

As for Loving v. Virginia, in that case Virginia courts had sentenced to prison a black woman and a white man who had been legally married in the District of Columbia and then returned to Virginia. The law also made it a crime to have sex with a person of another race.

If any state were to prosecute gay couples for getting married or having sex today, which seems almost inconceivable, it would properly be declared unconstitutional. But the best remedy for the less oppressive injustices to gays that are now being challenged is gradual democratic progress, not instantaneous judicial fiat.